1. Field of the Invention
The present invention relates to an optical mouse and, more particularly to an optical mouse capable of preventing an erroneous moving value of the optical mouse from outputting, when the optical mouse is spaced apart from the surface.
2. Description of the Related Art
Generally, in case of an optical mouse, as shown in FIG. 1, a light 7 emitted from a light source 8 is reflected by an operating surface 2, and the reflected light 6 passes through a lens 5 to be inputted to an image sensor 3 made of semiconductor process. The optical mouse 1 measures a quantity of the light projected to the image sensor 3 and stores a pattern made by comparing a difference between pixels of the image sensor 3. Then, a movement of the mouse is calculated by comparing a current pattern with a pattern made in a prior sample period. FIG. 2 is a block diagram of a prior integrated circuit for calculating a moving value of an optical mouse. Referring to the integrated circuit comprises an image sensor 21, consisted of hundreds of pixels, for outputting signals accumulated for a given time as a pixel unit, an A/D converter 22 for receiving the output of the image sensor 21 and converting the output into a digital signal, an image data processor 23 for receiving and calculating the output of the A/D converter 22 and calculating a moving value V(X,Y) of the optical mouse, and a system controller 24 for controlling a timing with an external system, and receiving and outputting the output of the image data processor 23.
A bottom surface of the optical mouse 1 should be in contact with the operating surface to ensure that a focus of an image on the operating surface is precisely made on the image sensor 3. If the bottom surface of the optical mouse 1 is spaced apart from the operating surface 2, when the entered light passes through the lens 5 to be input to the image sensor 3, the image is out of focused and thereby prevent the optical mouse 1 from calculating the precise movement. Therefore, the image reflected at the image sensor 3 looks like moving. However, since there is no actual horizontal movement of the optical mouse, a cursor appeared in the computer monitor should stop moving.
In case of a prior ball mouse, there is no problem as mentioned above since a ball of the mouse is not moved. However, in case of the optical mouse, the optical mouse calculates the erroneous moving value since the moving value of the mouse is calculated by depending upon a quantity of the entered light, when the optical mouse is spaced apart from the operating surface.